Cutting seamless hollow bodies



Patented Jan. 27, 1925.

BENEDIKT KNAEBEL, OF DUSSELDORF,

GER-MANY, ASSIG-NOR TO RHEINISCILE METALLWAAREN-UND MASCHINENFABRIK, OF DUSSELDORF-DERENDORF, GER- MANY, A CORPORATION OF GERMANY.

CUTTING SEAL/[LESS HOLLOW BODIES.

Application filed. May 20, 1924. Serial No. 14,660.

To all fro/wm t may concern.'

Be itY known that I, BENEDIKT KNAEBEL, a citizen of Germany, residing at Dusseldorf, Germany, Geistenstrasse 3, have invented certain new and useful Improvements 1n Cutting Seamless Hollow Bodies, of which the following is a specification.

l/Vhen seamless tubes or other hollow bod- 'ies are drawn according to known draw ing processes by means of a mandrel and drawing ring or rings, there is usually an irregular formation at the end of the tube last drawn through the ring. One side or various parts of that end are longer than the other side or the other parts, and also at the end the thicknesses of the walls of the tube vary around the circumference of the mandrel; on the one side or at various places they are thinner, almost to the ex` tent of being cut through, and thicker on the other side or at other places. Corners drawn out to a greater or less extent occur when hollow bodies, as often happens, are pressed out from ingots of square cross section. Irregularities at the end of the tube also occur when the ingots are not of rectangular but of circular cross section.

These irregularities in the formation of the tube make the stripping ofi' of the drawn member more difficult, since the material of the drawn tube frequently jams at the thin parts between the mandrel and the stripper with the result that, in consequence of the time lost thereby, the tube is still more firmly jammed on the mandrel and can only be removed from the mandrel by special processes which waste more time. When the tube, with or without difficulty, has been stripped off, it is always necessary that the end of the tube last drawn should then be trimmed at right angles to its axis, in order that a true end surface may be formed for the further working up of the tube, in case it has to undergo further mechanical operations, for example in the lathe, or in case further drawing operations either hot or cold are required. On account of the irregular formation of the end of the tube it is almost always necessary to cut ofi' the tube in an intermediate stage of the opera-tions and in many cases this necessitates its being carried backwards and forwards to and from the drawing works.

These drawbacks are obviated according to the invention as follows The irregular end is cut off during the drawing process while the tube is on the mandrel, and after the tube has been stripped from the mandrel, a tube of the yrequired length is thus obtained cut off exactly at right angles to the longitudinal axis, and which without any further processes can, for example, be placed on the lathe or undergo succeeding drawing operations.

In the accompanying' drawing: Figure l is a view illustrating the above-mentioned irregularities in the formation of the tube,

and also showing, in dotted lines, the hollow body in its first stage.

Figs. 2 and 3 illustrate two successi-ve stages of the process according to the present invention, and also show the preferred form of apparatus or device for carrying out the same.

Referring to Fig. 1, the hollow body A is placed in the usual manner on the mandrel B and is drawn out to a long hollow body or tube by drawing the mandrel with the work through one or more drawing rings arranged one behind the other. The cutting ring C is arranged on the mandrel B. It lies against a shoulder or projection of the mandrel itself or of the shaft D. The ring C can be moved to and fro on the free length of the mandrel and may be slid from it. This is for the purpose of replacing it for a new one or for sharpening it when the edge becomes dull. In addition its removability allows any desired number of rings to be placed on the mandrel and such rings can be of any suitable width depending upon the exact location desired to cut the tube or depending upon the length of the tube. In other words, a number of cutting rings or a single ring can be used depending upon the length of the tube so that very little of the tube need be wasted as the cut-ofi' portion. Heretofore it was necessary to keep a large supply of mandrels on hand which, of course, is expensive, but when cutting rings are used it is only necessary to keep on hand a few mandrels and a number of cutting rings of different widths. Its outer diameter is the same as that of the inner diameter of the drawing ring E or may be less than the inner diameter of the last drawing ring Eby Va small amount whichallowsthe .ring Citok assthrougli the ringE.' The inner edge :oi the drawing ring E and the outer edge of the cutting ring C Work together like the blades or' other cuttingdevices. On drawing out the tube, when the'work has passed the last drawing ring, the end ofthe tube lying beyond the drawing ring Spreads out against the cutting ring and, as the movement is continued, this end spreads out against the ring, somewhat as shown in Fig. 2. On the further approachuot the-cutting ring to the reduced internal part olf-the `drawingsring, the material 'otthe tubeis pressedintolhe sharp corner;l formed byitheizmandrel and the cut.- tingring- This corner is then entirely li-lled andfthefend off the tube isrtorced over. the cutting ring and sepa-rated from it with a cylindricaleend surface correspon'dingto the widthot-'the drawingming, and is `drawn backwardson the shaft otthe mandrel, as `shown in dotted linesinFig. The projection onthe1niandrel or the shaft D of the emandrel, which supports the cutting ring duringthe work andfdetern'iines its position rela-t ivielyl` to .the mandrel anditherewith the length of the cut olf tube, has adiameter which is, Iless than the (interY diameter ot the c uttipgA ring, f A i shoulder :is consequently Formed iat the rear-side. uThis shoulder lies dairifngi the i return` i stroke,V of; i the mandrel against a stripper G (Fig. 3) between itrand the-,draw ring=support F, Vso thatthettube is stripped lofi bysthefstripperfon` the return movementfof'fthe mandrel. =The projection onithemandrel; or the mandrel shaft forming fthe? shoulder ltorthey cutting .ring need notsfextend"V overthe Whole length 'of the mandrel. ylirlternatively, a .Y :ring can .be placed on themandreland can beisecured:A by ascrewthreadf kor other suitable; means. In

this Way it is possible Within certain limits to'alter the position of thecutting ring and, for example, to bring the front edge of the cutting ring again to the same position, if it has been shortened in consequence of wear.

The arrangement as described and which forms a preferred construction, embodies the use 'ot' a loose cutting ring. This cutting ring, WhichL is loose on the mandrel and can be moved to and fro and slid oli it, is not absolutely necessary. Obviously, an annular front edge formed of the material of the mandrel itselfpor the` shoulderl formed by` themandrel shaft, can be utilimdaisfthe cutting edge. The drawn hollowvmember that'has been cut off' to the requiredlength canlthen be'stripped oli by` stripping devices otherthau those described.

Having thus. described the naturcflof the said invention andfthe best `means Iknow of carryingi the same into practical effect, I claim ..l. Cutting apparatus `for enttingfseanrless-hollowtubes while said tubes are. on a mandrel comprising a cutting ring on said mandrel for cutting theend of the' tubefroni the finished portion. 2; Cutting apparatus for cutting seamlesshollow. tubes comprising a mandrel on which the tubes are. drawn through ardrawing ring, said` mandrel having ay shoulder thereon ;V `and a cuttingiring on said mandrel adapted to= abut against said shoulden tor cutting theend vofthe tube from the finished portion While said-tube islbeing drawn.

:In testimonywhereof lI have aixedzmy signature in presence of `two witnesses.

I BENEDIKT KNAEBEL.

Witnesses:

3 HENRY HAAS,

ToHR. 

